Catalysts utilizing oxygen-deficient metal oxide compound for removal of exhaust gas constituents

Abstract

The invention provides various solid catalysts for decomposition of exhaust gases. Catalysts include, among others, those of formula Ce 0 .5 La 0 .4 Sr 0 .1 Pd 0 .025 O 3x and BiCo 0 .8 Cu 0 .2 O 3x . The invention also relates to catalytic reactors for decomposition of exhaust gases utilizing solid catalysts of the invention. The invention further provides methods for synthesis of various mixed metal oxide catalysts for decomposition of exhaust gas pollutants.

We claim: 
     
       1. A solid catalyst for decomposition of exhaust gases comprising a single crystallographic phase material having the formula:   A.sub.1-y A'.sub.y-(1-x) B.sub.x MO.sub.2-Δ     where 0≦y≦1; 0≦x≦1; Δ is a number that renders the composition charge neutral; A is selected from the group consisting of lanthanides, actinides, and group IV metals; A' is selected from the group consisting of group 3+ lanthanide metal ions Ga 3+ , In 3+ , Sb 3+ , Bi 3+ , Y 3+ , and Sc 3+  ; B is a 2+metal ion selected from the group consisting of the metal ions Pb 2+ , Sn 2+ , Cu 2+ , Ba 2+ , Sr 2+ , and Ca 2+  ; and M is a metal ion selected from the group consisting of the metal ions of V, Cr, Mn, Fe, Ni, Ag, Au, Co, Cu, Pd, Pt, Re, Ru, Rh, Os, or Ir.   
     
     
       2. A catalytic reactor for decomposition of exhaust gas pollutants which comprises: a casing having an entrance port, an exit port and a passage therebetween for the movement of said gases from the entrance port to the exit port; and   a catalyst according to claim 1 in said passage wherein said gases contact said catalyst before exiting said casing.   
     
     
       3. A catalytic reactor according to claim 2 further comprising: a honeycomb matrix having inner and outer surfaces; and   wherein said catalyst is a layer of catalyst on the inner surfaces of said honeycomb matrix and wherein said gases contact said inner surfaces.   
     
     
       4. A solid catalyst for decomposition of exhaust gases comprising a single crystallographic phase material having the formula:   A.sub.2 B.sub.2 MO.sub.7     where:   A is selected from the group consisting of lanthanides and actinides;   B is selected from the group consisting of 3+ lanthanide metal ions and Ga 3+ , ln 3+ , Sb 3+ , Bi 3+ , y 3+ , and Sc 3+  ; and   M is a metal ion selected from the group consisting of the metal ions of V, Cr, Mn, Fe, Ni, Ag, Au, Co, Cu, Pd, Pt, Re, Ru, Rh, Os, or Ir.   
     
     
       5. A catalytic reactor for decomposition of exhaust gas pollutants which comprises: a casing having an entrance port, an exit port and a passage therebetween for the movement of said gases from the entrance port to the exit port; and   a catalyst according to claim 4 in said passage wherein said gases contact said catalyst before exiting said casing.   
     
     
       6. A solid catalyst for decomposition of exhaust gases comprising a single crystallographic phase material having the formula:   A.sub.1-x A'.sub.x B.sub.1-y B'.sub.y MO.sub.3-Δ     where 0≦y≦1; 0≦x<1; Δ is a number that renders the composition charge neutral; A is Bi 3+  or Sb 3+  ; A' is selected from the group consisting of Pb 2+ , Sn 2+ , Cu 2+ , Ba 2+ , Sr+, or Ca 2+  ; B is Co 3+ , Fe 3+ , Mn 3+ , Ni 3+ , Cr 3+ , or V 3+  ; B' is selected from the group consisting of Cu 2+ , Ni 2+ , Fe 2+ , and Co 2+  ; and M is selected from the group consisting of Cu, Ag, Au, Pd, Pt, Re, Ru, Rh, Os or Ir.   
     
     
       7. A catalytic reactor for decomposition of exhaust gas pollutants which comprises: a casing having an entrance port, an exit port and a passage therebetween for the movement of said gases from the entrance port to the exit port; and   a catalyst according to claim 6 in said passage wherein said gases contact said catalyst before exiting said casing.   
     
     
       8. A solid catalyst for decomposition of exhaust gases comprising a single crystallographic phase material having the formula Ce 0 .5 La 0 .4 Sr 0 .1 Pd 0 .025 O 2-x . 
     
     
       9. A catalytic reactor for decomposition of exhaust gas pollutants which comprises: a casing having an entrance port, an exit port and a passage therebetween for the movement of said gases from the entrance port to the exit port; and   a catalyst according to claim 8 in said passage wherein said gases contact said catalyst before exiting said casing.   
     
     
       10. A solid catalyst for decomposition of exhaust gases comprising a single crystallographic phase material having the formula BiCo 0 .8 Cu 0 .2 O 3-x . 
     
     
       11. A catalytic reactor for decomposition of exhaust gas pollutants which comprises: a casing having an entrance port, an exit port and a passage therebetween for the movement of said gases from the entrance port to the exit port; and   a catalyst according to claim 10 in said passage wherein said gases contact said catalyst before exiting said casing.   
     
     
       12. A method for synthesizing a catalyst for decomposition of exhaust gas pollutants which comprises the steps of: (A) providing a compound selected from the group consisting of AO 2  and A(CO 3 ) 2  wherein the A element is selected from the group consisting of 4+ ions of the lanthanides, actinides and Group IV metals;   (B) providing the compound A' 2  O 3 , where the A' element is selected from the group consisting of the 3+ ions, La 3+ , Ga 3+ , ln 3+ , Sb 3+ , Bi 3+ , y 3+ , and Sc 3+  ;   (C) providing a compound selected from the group consisting of BO and BCO 3  where the B element is selected from the group consisting of the 2+ metal ions, Pb 2+ , Sn 2+ , Cu 2+ , Ba 2+ , Sr 2+ , and Ca 2+  ;   (D) providing a compound selected from the group consisting of M 2  O, MO, M 2  O 3 , MO 2 , MNO 3 , M(NO 3 ) 2 , M(NO 3 ) 3 , and M(NO 3 ) 4  where M is a metal ion taken from the group consisting of the metal ions of V, Cr, Mn, Fe, Ni, Ag, Au, Co, Cu, Pd, Pt, Re, Ru, Rh, Os, and Ir;   (E) mixing quantities of the compounds of steps (A) through (D) together so that the stoichiometric ratio of A/A' is 1.25, the stoichiometric ratio of A/B is 5 and the weight fraction of M in the mixture is less than 2%;   (F) ball milling the mixture of step (E) to form a powder; and   (G) calcining said powder at a temperature between 1000° C. and 1400° C.   
     
     
       13. The method of claim 12 wherein the mixture is calcined at temperatures above 1200° C. 
     
     
       14. The method of claim 12 wherein the compound of step (D) is combined with the compounds of steps (A)-(C) in the stoichiometric ratio of A/M is 20. 
     
     
       15. The method of claim 12 wherein the compound of step D is Pd(NO 3 ) 2  and wherein the compound of step (D) is combined with the compounds of steps (A)-(C) in the stoichiometric ratio of A/Pd is 20. 
     
     
       16. The method of claim 14 wherein A is Ce 4+ , A' is La 3+ , B is Sr 2+   and M is Pd 2+ . 
     
     
       17. The method of claim 12 wherein said catalyst is a catalyst for removal of nitrogen oxides from exhaust gas. 
     
     
       18. The catalyst prepared by the method of claim 12. 
     
     
       19. A method for synthesizing a catalyst for decomposition of exhaust gas pollutants which comprises the steps of: (A) providing a compound selected from the group consisting of AO 2  and A(CO 3 ) 2  wherein A is selected from the group consisting of Bi 3+   and Sb 3+  ;   (B) providing the compound BO and BCO 3 , where B is selected from the group consisting of Co 3+ , Fe 3+ , Mn 3+ , Ni 3+ , Cr 3+ , and V 3+  ;   (C) providing a compound selected from the group consisting of B'O and B' CO 3  where B is selected from the group consisting of Cu 2+ , Ni 2+ , Fe 2+ , and Co 2+  ;   (D) providing a compound selected from the group consisting of M 2  O, MO, M 2  O 3 , MO 2 , MNO 3 , M(NO 3 ) 2 , M(NO 3 ) 3 , and M(NO 3 ) 4  where M is a metal ion selected from the group consisting of the metal ions of Ag, Au, Cu, Pd, Pt, Re, Ru, Rh, Os, and Ir;   (E) mixing quantities of the compounds of steps (A) through (D) together so that the stoichiometric ratio of the weight fraction of M in the mixture is less than 2%, the stoichiometric ratio of A/B is 1.25 and the stoichiometric ratio of A/(B'+M) is 5;   (F) ball milling the mixture of step (E) to form a powder; and   (G) calcining said powder at a temperature between 600° C. and 850° C.   
     
     
       20. The method of claim 19 wherein A is Bi 3+ , B is Co 3+ , B' is Cu 2+   and M is a metal ion of Cu. 
     
     
       21. The method of claim 19 wherein said catalyst is a catalyst for removal of nitrogen oxides from exhaust gas. 
     
     
       22. A catalyst prepared by the method of claim 19. 
     
     
       23. A method for synthesizing a catalyst for the decomposition of exhaust gas pollutants which comprises the steps of: (A) providing a compound A(NO 3 ) 3 , where A is selected from the group consisting of 4+ ions of the lanthanides, actinides and Group IV metals;   (B) providing a compound A'(NO 3 ) 3 , where A' is selected from the group consisting of the 3+ ions, La 3+ , Ga 3+ , In 3+ , Sb 3+ , Bi 3+ , y 3+ , and Sc 3+  ;   (C) providing a compound B(NO 3 ) 2 , where B is selected from the group consisting of the 2+ metal ions, Pb 2+ , Sn 2+ , Cu 2+ , Ba 2+ , Sr 2+ , and Ca 2+  ;   (D) providing a compound MNO 3 , M(NO 3 ) 2 , M(NO 3 ) 3 , and M(NO 3 ) 4  which is a soluble nitrate where M is a metal ion selected from the group of metal ions of V, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Pt, Re, Ru, Rh, Os, and Ir;   (E) dissolving quantities of the compounds of steps (A)-(D) in water to form a solution wherein the stoichiometric ratio of A/A' is 1.25, the stoichiometric ratio of A/B is 5 and the weight fraction of M in the mixture is less than 2%;   (F) adding to the solution of step (E) a sufficient amount of a precipitation agent selected from the group consisting of Na 2  CO 3 , K 2  CO 3 , NaOH, KOH, sodium oxalate, and potassium oxalate to form a precipitate of the compounds of steps (A)-(D);   (G) collecting the resulting precipitate of step (F);   (H) washing the collected precipitate of step (G) to remove excess precipitating agent; and   (I) calcining the washed precipitate of step (H) at a temperature between 200° C. and 600° C.   
     
     
       24. The method of claim 23 wherein the stoichiometric ratio of A/M in said mixture is 20. 
     
     
       25. A method for synthesizing a catalyst for the decomposition of exhaust gas pollutants which comprises the steps of: (A) providing a compound A(NO 3 ) 3 , where A is selected from the group consisting of Sb 3+   and Bi 3+  ;   (B) providing a compound B(NO 3 ) 3 , where B is selected from the group consisting of Co 3+ , Fe 3+ , Mn 3+ , Ni 3+ , Cr 3+ , and V 3+  ;   (C) providing a compound B' (NO 3 ) 2 , where B' is selected from the group consisting of Cu 2+ , Ni 2+ , Fe 2+ , and Co 2+  ;   (D) providing a compound MNO 3 , M(NO 3 ) 2 , M(NO 3 ) 3 , and M(NO 3 ) 4  which is a soluble nitrate where M is a metal ion selected from the group of metal ions of Cu, Ag, Au, Pd, Pt Re, Ru, Rh, Os, and Ir;   (E) dissolving quantities of the compounds of steps (A)-(D) in water to form a solution wherein the fractional weight ratio of M to the total weight of dissolved compounds is less than 2%, the stoichiometric ratio of A/B is 1.25, and the stoichiometric ratio of A/(B'+M) is 5;   (F) adding to the solution of step (E) a sufficient amount of a precipitation agent selected from the group consisting of Na 2  CO 3 , K 2  CO 3 , NAOH, KOH, sodium oxalate, and potassium oxalate to form a precipitate of the compounds of steps (A)-(D);   (G) collecting the resulting precipitate of step (F);   (H) washing the collected precipitate of step (G) to remove excess precipitating agent; and   (I) calcining the washed precipitate of step (H) at a temperature between 200° C. and 600° C.   
     
     
       26. The method of claim 25 wherein A is Bi 3+ , B is Co 3+ , B' is Cu 2+   and M is a metal ion of Cu. 
     
     
       27. The method of claim 25 wherein said catalyst is a catalyst for removal of nitrogen oxides from exhaust gas. 
     
     
       28. The catalyst prepared by the method of claim 25.